This application requests support for the development of new methods for the incorporation of novel amino acids into recombinant proteins. Computational and experimental studies will be combined to design mutant forms of the aminoacyl-tRNA synthetases that are capable of efficient activation of amino acid analogs bearing reactive functional groups. Special attention will be given to amino acids that carry alkyne, azide and ketone functional groups, in order to provide powerful new chemistries for use in the engineering of natural and artificial proteins. Computational design will be evaluated in comparison with experimental approaches that involve multiple rounds of mutagenesis and selection, and computational predictions will be assessedby comparison with the results of in vitro kinetic studies of amino acid activation. Cell free transcription - translation systems will be used as appropriate to identify and address limitations due to poor amino acid transport. The new chemistries to be developed in this work will open new opportunities in the design of engineered biomaterials.